Chemical Polishing of Aluminum and Aluminum Alloys
In the manufacturing industry, aluminum and aluminum alloys are used for a wide range of applications from aerospace engineering to consumer products. It is essential to ensure the highest quality surfaces in applications such as automotive or aeronautical objects, where polished surfaces have higher corrosion resistance and improved fatigue strength. To reach this goal, a common practice is to finish the aluminum parts with chemical polishing.
Chemical polishing (also known as chem-milling or etch-milling) is a method of finishing aluminum and aluminum alloys that involves selectively passivating exposed surfaces with a solution of acids, bases and salts. The acid dissolves exposed aluminum while leaving the underlying substrate intact. This process can be used to remove surface defects such as ridges and tool marks, as well as to achieve a polished, mirror like finish on aluminum surfaces. Chemical polishing also improves corrosion resistance and fatigue strength of aluminum surfaces.
The chemical polishing process begins by submerging the aluminum in the etchant solution for a few minutes to allow for the desired metallurgical polishing action to take place. The etchant is then removed, and the aluminum is rinsed and dried. The finished surface can then be inspected for weathered or oxidized areas, and any additional polishing steps may be taken if needed.
To achieve the desired polishing result, it is important to match the etchant solution with the specific alloy being processed. Different types of aluminum alloys have different chemical compositions and require different etching solutions. For example, aluminum alloys that contain copper, magnesium, or zinc will require a different etching solution than aluminum alloys that only contain aluminum. In addition, the etching time must be adjusted depending on the thickness of the aluminum alloy being processed.
The chemical polishing process is essential in many industries, including aerospace engineering and electrical engineering. It provides increased corrosion resistance and improved fatigue strength, as well as producing a brighter, smoother finish on aluminum and aluminum alloys. Chemical polishing can be used on a variety of products, from automotive parts to consumer goods, ensuring the highest quality standards are met.
